Thyroid cancer is a cancerous growth of the thyroid gland, which is located in the neck. Differentiated thyroid cancer is the most common type of thyroid cancer. The National Cancer Institute estimates that 60,220 Americans will be diagnosed with thyroid cancer and 1,850 will die from the disease in 2013.

Nexavar works by inhibiting multiple proteins in cancer cells, limiting cancer cell growth and division. The drug's new use is intended for patients with locally recurrent or metastatic, progressive differentiated thyroid cancer that no longer responds to radioactive iodine treatment.

"Differentiated thyroid cancer can be challenging to treat, especially when unresponsive to conventional therapies," said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research. "Today's approval demonstrates the FDA's commitment to expediting the availability of treatment options for patients with difficult-to-treat diseases."

The safety and effectiveness of Nexavar were established in a clinical study involving 417 participants with locally recurrent or metastatic, progressive differentiated thyroid cancer that does not respond to radioactive iodine treatment. Nexavar increased the length of time patients lived without the cancer progressing (progression-free survival) by 41 percent. Half of patients receiving Nexavar lived without cancer progression for at least 10.8 months compared to at least 5.8 months for participants receiving a placebo.

The most common side effects in patients treated with Nexavar were diarrhea, fatigue, infection, hair loss (alopecia), hand-foot skin reaction, rash, weight loss, decreased appetite, nausea, gastrointestinal and abdominal pains and high blood pressure (hypertension). Thyroid stimulating hormone, a potential promoter of thyroid cancer, is more likely to become elevated while on treatment with Nexavar, requiring adjustment of thyroid hormone replacement therapy.

The FDA completed its review of Nexavar's new indication under its priority review program. This program provides for an expedited, six-month review for drugs that may offer a significant improvement in safety or effectiveness of the treatment, prevention or diagnosis of a serious condition. Nexavar also received orphan-product designation by the FDA because it is intended to treat a rare disease or condition.

The FDA approved Nexavar to treat advanced kidney cancer in 2005. In 2007, the agency expanded the drug's label to treat liver cancer that cannot be surgically removed.

Nexavar is co-marketed by Bayer HealthCare Pharmaceuticals Inc., based in Wayne, N.J., and Onyx Pharmaceuticals, based in South San Francisco, Calif.